In November, Missouri was one of four states that voted to change how political boundaries are drawn in order to limit gerrymandering. The constitutional amendment passed in all corners of the increasingly conservative state. Now some members of both political parties want to scrap the new system before it even launches. St. Louis Public Radio's Jason Rosenbaum reports.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED CROWD: (Chanting) Yes on 1, yes on 1, yes on 1.

JASON ROSENBAUM, BYLINE: A bowling alley in St. Louis was the scene of a raucous election night celebration. On a night where Democrats saw an incumbent U.S. senator lose, many in the party like St. Louis Treasurer Tishaura Jones were heartened by the passage of Amendment 1, which overhauled state legislative redistricting.

TISHAURA JONES: And so Amendment 1 gives a voice back to the people who elected legislators to go to Jefferson City to represent their interests.

ROSENBAUM: But supporters had little chance to exhale. Just a couple of days after Election Day 2018, Republicans, like incoming Senate Leader Dave Schatz openly talked about repealing the new system.

DAVE SCHATZ: I think it's a major concern for this majority and how that is going to impact the future. And I do think that there's issues that are going to be addressed there.

ROSENBAUM: Schatz and other top Republicans want to either alter or repeal the voter-enacted redistricting plan. That plan takes much of the power away from a commission of politically connected people and places it in the hands of an independent demographer. Maps would have to emphasize competitiveness and partisan fairness.

But Republican critics see Amendment 1 as an attempt by Democrats to chip away at huge GOP majorities in the state legislature. And since Democrats are largely clustered in St. Louis and Kansas City, Senator-elect Cindy O'Laughlin says Amendment 1's criteria will create weirdly shaped districts that will be extremely difficult to represent.

CINDY O'LAUGHLIN: I see no reason for, you know, a largely Republican area to be all of a sudden connected to something that's distant from there to try to engineer the results. I think that's wrong.

ROSENBAUM: Any change or repeal to the redistricting process would have to go before Missouri voters again. But Sean Soendker Nicholson says these complaints are sour grapes. Nicholson was the campaign manager for Amendment 1, which also included curbing lobbyist gifts and making legislative emails open records. He says Amendment 1's changes will give political parties a chance to compete in parts of the state where they had a huge disadvantage.

SEAN SOENDKER NICHOLSON: Everyone believes in a fair shake, and everyone believes in competition. And everyone believes a system that's transparent. Those are universal values. There aren't - those aren't partisan values.

ROSENBAUM: But it's not just Republicans who are up in arms. African-American Democrats like State Representative-elect Maria Chappelle-Nadal contend the only way to create more competitive political maps will be to reduce the percentage of black residents in those districts. Chappelle-Nadal believes this will lead to more white politicians winning in districts with sizable minority populations, which she says will hurt communities like Ferguson that need strong black representation.

MARIA CHAPPELLE-NADAL: After what has happened in St. Louis County and the state of Missouri, I cannot by any means give up the opportunity for African-Americans to represent or any other minority to represent other minorities.

ROSENBAUM: Amendment 1 proponents point to language in the amendment aimed to protect minority voters. The measure also has support from a number of civil rights groups. Nicholson points out that the voters in Republican and Democratic parts of the state backed the initiative, and lawmakers should pay attention.

NICHOLSON: I think the governor and other legislators who are thinking about undoing the will of the voters should look long and hard at those numbers and think about the message that voters are trying to send.

ROSENBAUM: Even if the legislature acts this year, it likely won't be known if voters decide to stick with the new system until 2020 just before the new round of redistricting starts. For NPR News, I'm Jason Rosenbaum in St. Louis. Transcript provided by NPR, Copyright NPR.